At least 20 people were killed Thursday when a suicide bomber targeted a meeting of clan chiefs and tribal leaders in a village to the west of Baghdad, media reports said.
Al-Arabiya news channel said that the blast occurred when a suicide attacker detonated himself in the local council in Karma village in Anbar province, reported dpa.
The attacker managed to enter through an unguarded gate, al- Arabiya said.
Senior local officials and clan chiefs were reported to be among the killed, while US troops were believed to be among the injured.
Firm figures about the injured were not yet available, while the death toll was expected to rise, al-Arabiya said.
Separately, the US military said one of its soldiers was killed by an armour-piercing charge in the predominantly Shiite area of eastern Baghdad, the latest in a surge of violence that saw at least nine soldiers killed this week.
The US military says the charges come from Iran.
The fatality pushes the number of soldiers who died in June to at least 26.
This figure is higher than the death toll of 19 in May.
In another news, the US military said its troops killed three "criminals" after they were attacked by small arms fire near Baghdad International Airport about 8:40 am on Wednesday.
The three people, who were travelling in a car, fired on the soldiers while their military convoy was stopped on the side of the road, according to the military.
The soldiers returned fire, causing the vehicle to run off the road and strike a wall. The vehicle eventually exploded and all three occupants were killed, the military said.
The attack left bullet holes in the convoy vehicle, the statement said, adding that a weapon was recovered from the wreckage.
Iraqi officials were quoted as saying that the bodies were identified as those of employees at a bank at the airport. One of them was a woman.
The incident is one of several recent episodes in which US and Iraqi officials have given contradictory accounts of how incidents occurred.
In a similar episode on Wednesday, witnesses told Deutsche Presse- Agentur dpa that five Iraqis from the same family were killed in a US strike on a house in the town of Tikrit.
Iraqi local officials confirmed the killing of civilians.
But the US military offered a sharply different account. It said an "al-Qaeda terrorist" had opened fire on US soldiers.
The soldiers had to surround the building where the man was hiding, the US military said in a statement, adding that when he refused to surrender they had to call in the airstrike.